This invention relates to thermal insulation and particularly to thermal insulation for buildings. Many types of insulation adapted to be placed between a source of heat and a sink for the same are known in the art. Such insulation is useful in keeping the internal volume of a structure warmer or colder than the surrounding atmosphere. When such is to be accomplished, insulation is included in the walls, the ceiling and sometimes the floor surrounding such structures so that they exhibit as low a thermal transmission coefficient as possible consistent with the economics produced.
In particular, it is known to utilize materials provided with internal subdivisions so as to reduce direct heat conductivity paths and to suppress the tendency of gases trapped in the internal subdivisions to transfer heat through natural convection. Commonly employed insulating materials include mineral wool, glass fiber batts, plastic and elastomeric foams, low-density ceramics and others. They operate on the principle of defining a volume with the least possible solid mass while separating air entrapped in the matrix into small independent cells in which convection is greatly diminished.
It is also well known that reflective surfaces, such as bright metal foils have a tendency to reflect incident radiant heat, a form of electomagnetic radiation, toward the source. The combination of the aforementioned insulating techniques is also known, for example, in commercial glass fiber insulation disposed in paper enclosed batts having one or more surfaces thereof composed of, or laminated with, an aluminum foil surface. Such materials are commonly installed between the studs in stud wall structures and provide a barrier to heat transfer by conduction, convection, and radiation. In some applications, economically effective insulation can be provided by merely placing spaced layers of reflective foil parallel to the surface to be insulated, and mounting and orienting the foil layers so convection and conduction are reduced. Typical structures of this type are manufactured by Louis Hafers Co., 1514 Chestnut Street, Alhambra, Calif. and are described in Schwartz, U.S. Pat. No. 2,750,313. To be efficient, the reflective layers must be spaced from each other and tightly held laterally against adjacent structure such as the supporting studs thereof. Unfortunately, such constuctions with multiple layers of spaced foil extending between side supports have rectangular cross-sections which can be attached to the structure only at three corners thereof, as the fourth corner becomes inaccessible during installation. Therefore, although such structures are lightweight, relatively inexpensive and theoretically have good insulating characteristics, the difficulty of their complete installation without insulation faults reduces their effectiveness considerably or makes their installation extremely complex.